Tag Archives: walkability

Electric cars will not save us

A nice picture of a two-way protected bike lane, with lots of bikes using it.

In addition to lots of twitter arguments about the Green New Deal, my feed has also been full of arguments about the relative role for electric cars.

I get the appeal of electric cars: it’s hard to envision any scenario where we address climate change without relying on electrification of our vehicle fleet. It’s a technology that has lots of promise. These cars appeal to our desires for innovation, yet still recall previous moments of national pride.

All that said, the simple math on emissions remains clear: electric cars alone won’t solve our surface transportation GHG problems. We have to drive less.

A number of articles in recent months have tried to emphasize this point, but they don’t often seem to break through. I’d like to highlight this one from Meredith Hankins:

…when we’re all driving zero-emission vehicles that plug into a zero-carbon grid, our transportation emissions will indeed be extremely low carbon. But here’s the thing: that future is a long way off. California’s ZEV mandate calls for only about 8% of new vehicle purchases to be ZEVs by 2025–and that’s just new vehicles. The average car sold today will be on the road for at least 11 years, locking in a decade plus of GHG emissions for every non-ZEV sold. In addition to our long-term electrification plans, we have to focus on strategies to reduce emissions from those non-ZEVs in the near term by getting them off the road.

The basic facts about cars (regardless of their power source) haven’t changed. They’re remarkably large and inefficient vehicles. They take up large spaces and require lots of energy to move.

Since the ultimate goal here is to reduce GHG emissions, making transport more energy-efficient in total is an important intermediate objective, we need to not just shift the energy sources to electricity, but also consider the overall efficiency.

Limiting automotive GHG emissions isn’t simply about making cars cleaner, but also about limiting how much we use these inefficient modes of transport. In other words, driving less.

Don’t take my word for it, just listen to the IPCC. Here’s Meredith Hankins again:

But here’s the thing: we can’t afford to ignore significant climate mitigation measures just because they are politically difficult.
The IPCC’s recent bombshell report notes that “demand-side mitigation and behavioural changes” are going to be needed to avoid the worst climate change impacts. Transportation mitigation pathways for limiting global warming to less than 1.5 degrees require not just “[t]echnology-focused measures,” but also strategies based on “[s]tructural changes that avoid or shift transport activity” that have “received lesser attention in most global transport decarbonisation pathways up to now.”  

(emphasis added)

To make things a bit more tangible, here are the kinds of targets California thinks they need to hit:

  • Quadruple the proportion of trips taken by foot by 2030 (from a baseline of the 2010–2012 California Household Travel Survey).
  • Strive for a nine-fold increase in the proportion of trips taken by bicycle by 2030 (from a baseline of the 2010–2012 California Household Travel Survey).

Dramatically increasing bike and walk trips (and doing so immediately) is both a simple goal, yet a radical one. It’s a radical change from the status quo, but also something simple enough to do. Meeting these goals doesn’t require any technological miracles (or even any new technology at all).

Breaking it down a bit further, hitting those targets realistically requires policies that impact both the supply of places that support bike and walk trips, as well as policies that increase demand for them.

On the supply-side, hitting these targets means increasing the supply of places suitable for bike and pedestrian trips: safe bike and pedestrian infrastructure, expanded at a massive scale. These are proven and relatively simple tasks, but the scale called for here is still daunting. Ask anyone who’s worked on these projects about the effort required to build 9x as many protected bike lanes.

Additionally, all of these supply-side elements are things local governments can do. For all of the Mayors out there talking a good game on climate, here’s the biggest bang for your buck. Furthermore, places that are already walkable and bikeable will be far better suited to accommodate shifting behavior. It’s entirely plausible to picture a nine-fold increase in biking in a big city.

The demand side perhaps more important in shifting behavior, particularly for pricing incentives (against cars, for walking/biking/transit). Some of this can happen at the local level (parking policy, pricing) while others will require state-level and national action. Just look back at the increases in transit usage when gas prices go up.

Intersection density & centrality

What is the best method to quantify what makes a place walkable?  The Journal of the American Planning Association recently published some powerful documentation from Robert Cervero and Reid Ewing on the value of pedestrian-oriented design (following up on yesterday’s links).  Grist has the article (hat tip to Planetizen), citing Laurence Aurbach’s PedShed blog – again, the “Three D’s” or urbanism emerge front and center – density, diversity, and design:

Their findings? Of all the built environment measurements, intersection density has the largest effect on walking — more than population density, distance to a store, distance to a transit stop, or jobs within one mile. Intersection density also has large effects on transit use and the amount of driving. The authors comment,

This is surprising, given the emphasis in the qualitative literature on density and diversity, and the relatively limited attention paid to design.

In other words, intersection density is the most important factor for walking and one of the most important factors for increasing transit use and reducing miles driven, but gets relatively little attention in research and in public policy.

In other words, the other two D’s (density and diversity) get more play than design.  Perhaps that’s because density and diversity (of land use, of people, of incomes, etc) were easier to quantify than something as seemingly subjective as design.

Intersection_Density

Kaid Benfield ties these principles to those angry about the ever expanding oil slick in the Gulf of Mexico, hitting on another theme of the research – location:

The study’s key conclusion is that destination accessibility is by far the most important land use factor in determining a household or person’s amount of driving.  To explain, ‘destination accessibility’ is a technical term that describes a given location’s distance from common trip destinations (and origins).  It almost always favors central locations within a region; the closer a house, neighborhood or office is to downtown, the better its accessibility and the lower its rate of driving.  The authors found that such locations can be almost as significant in reducing driving rates as other significant factors (e.g., neighborhood density, mixed land use, street design) combined.

The clear implication is that, to enable lifestyles with reduced driving, oil consumption and associated emissions, environmentalists should continue to stress opportunities for revitalization and redevelopment in centrally located neighborhoods.  As Ewing and Cervero put it:  ‘Almost any development in a central location is likely to generate less automobile travel than the best-designed, compact, mixed-use development in a remote location.’

Aurbach is quick to note the limitations of the study, but even with those this is an exciting quantification and potential metric for walkable and sustainable design.  It builds off the Jacobs legacy of ‘short blocks’ and adds some science behind recent GGW posts from Erik Bootsma and Daniel Narin on the variety and histories of street grids.  This kind of research lends weight to the anecdotal accounts of Portland’s small blocks resulting from the belief that corner lots were more valuable, as well as ideas of better utilization of alley space – such as this recent post from Richard Layman.